What bolt / screw do i use here ?

[marsaday]

I have to secure some metal plates to my steel channel in my attic conversion.

They attach to the truss frame in the centre of the roof (holding it up) and also attach to my new steel.

I will drill through the wood parts and bolt a plate either side. However, i also need to bolt the bottom of the plate onto the steel. I have a 12mm hole drilled in these plates and so i need to drill through my steel at this point. Inside the steel is sat a 75mm deep joist.

What would i use to secure the plate to the steel and into the wooden joist ?

If there is nothing out there i will just have them welded in place.

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[Deluks]

If there isn't space between the timber and inner flange, then use a drill/chisel on the timber and make enough room for a nut to fit in there. Then use a very short or cropped bolt/studding and drop it in from the top. Hold the nut in place with a spanner and tighten it up from the top.

Stuff you probably know by now:
If cutting studding or bolts, be sure to put the nut on first, then after you've cut you unscrew the nut to clear any burrs.

Drilling into your steel will be easy with a HSS bit in a drill (cordless will do) If you've got a set go with 6,8,10,12 in that order and it will be fairly quick.

 

[theoldun]

If the 75mm joist is up tight to top flange of steel, drill steel and rattle M10 Hex head coach screw in.
oldun



Duke Look at your messages
oldun

 

[marsaday]

Chopping out to get a nut under the steel is not an option really.

I will look into what oldun has mentioned. Thanks for info.

 

[Hitachimad]

Myself, id drill through both and put a nice coach screw in, its only to stop it moving sideways i gather?

If it really has to be fixed to the steel, you could drill and tap it, but thats hassle unless you have the stuff to do that.


If youve got more welding to do up there later, just get a couple of stitches put on it, otherwise thats a last resort.

Oh, and see if they will finish welding the bracket together... seems to be a bit of weld missing at each end of the run. A pet hate of mine

 

[marsaday]

Well i think i will screw into the wood and then get the blacksmith to come out and do some welding. To make sure.

The reason why i am needing this plating is that the king post is part of a huge trianglular frame. In the middle spurring off the kingpost (on each side) i have 2 struts holding up the timbers running down each section of the roof. These need to be cut to put in 2 doorways. Thats why i am using all these plates.

My joist hangers on the steel side are just folded over at the moment (would be nailed if they were going into timber). So do you think i should get these welded into the steel as well ?

pic is enclosed showing the frame.

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